And it was a particularly small vehicle – probably the smallest liquid fuelled
1st stage vehicle in history? At the time at least.
It achieved that not from its specific impulse, but from its *density*
specific impulse.
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Michael Kelly (Redacted sender "mskellyrlv" for DMARC)
Sent: Tuesday, 2 March 2021 11:23 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: WFNA with terpentine
The original French space launch vehicle, the Diamant, used WFNA and turpentine
in the first stage. They avoided hard starts by incorporating a 250 lbm slug
of furfuryl alcohol in the fuel feed line.
Isp was less than impressive; sea level Isp was 203 seconds, vacuum was 233.
Not very impressive. However, the chamber pressure was only 255 psia, and the
area ratio only 3.6. That allowed them to pressure feed the propellants,
resulting in a very short development cycle. The engine developed almost
70,000 pounds at sea level, and the vehicle GLOW was just a little over 40,000
pounds. From a system design standpoint, given their goals (join the USSR and
US as a space launch nation, without breaking the bank), it was a remarkably
good solution.
I expect that Peter Beck, who evidently advised them, knows all of this.
On March 1, 2021 at 6:15 PM, Henry Spencer <hspencer@xxxxxxxxxxxxx
<mailto:hspencer@xxxxxxxxxxxxx> > wrote:
On Tue, 2 Mar 2021, Troy Prideaux wrote:
[WFNA/turpentine]
Yeah, it�s a strange selection given the handling issues of the oxidizer.
It also has a reputation for hard starts -- yes, it's hypergolic, indeed
one of the first hypergolic combinations discovered, but it has enough
ignition delay to be a bit marginal.
If I were them, I'd worry a bit about whether successful results with one
batch of turpentine today would translate into success with another batch
tomorrow, given that the composition is not really standardized. I would
particularly worry about whether smooth starts today would become hard
starts tomorrow.
Henry